That was quick, thanks! Clearly, Jon realized he'd never play the piano and stored it away in the attic, where it dropped through the ceiling in the 1985 strip.
My pleasure, doing searches for silly stuff gives me life! 😊 Here's a bonus strip featuring a piano that I didn't include because there's no indication that it belongs to Jon (unless he tried to murder Garfield with it before putting it in the attic)